Systems and Methods for Water Purification Using Supercritical Water Oxidation

ABSTRACT

Systems and methods using the properties of supercritical water to allow raw air including a contaminant to be combined with water and to be purified in a supercritical water oxidation (SCWO) process. A supercritical water oxidation (SCWO) air purifier will generally take in a mixture of water and raw air which includes oxygen via a pumping and mixing apparatus, put the mixture into a supercritical water reactor (SCWR), and run the resultant effluent stream through a system for separating the water from the resultant clean air and the other relatively harmless outputs of the supercritical water reactor (SCWO).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a Continuation of U.S.Utility patent application Ser. No. 10/971,391 filed Oct. 22, 2004, andcurrently pending. The entire disclosure of which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure relates to the field of air purification and convertingair which is unsafe for human use into air which humans can safelybreathe. In particular, this disclosure relates to the use ofsupercritical water oxidation to purify air.

2. Description of the Related Art

In recent years the need to segregate individuals from dangeroussubstances in the air has become one of increasing interest. All humanbeings must breathe and the introduction of airborne agents into the airthey inhale creates a dangerous situation whereby individuals can bekilled or injured and can strain medical response capability in an area.While all environmental air contains some impurities which can harmthose breathing it, such as cold viruses and allergen molecules, modernwarfare, terrorism, technology changes, and increasing globalizationhave led to an increased likelihood of larger scale contamination of airwhere sources of clean air can become quickly necessary to preventcatastrophic outcomes.

The danger of a chemical, biological, or nuclear weapon being unleashedon military forces, or on civilian centers, is a nightmare scenario formany government organizations. Such an attack can stymie militaryeffectiveness or bring day to day economic activity to a grinding halt.Even without the purposeful use of nuclear, biological, or chemicalweapons, the possibility of accidents involving these agents inpopulated areas is also a danger and governments must be able to respondto protect the citizenry. Still further, increases in globalization haveled to increased danger of communicable disease. The recent Severe AcuteRespiratory Syndrome (SARS) outbreak and fear of other dangerous naturalcontagions transmitted in the air has dramatically highlighted the needfor clean air. In public forums such as stadiums, malls, conventioncenters, or airplanes where a large population is breathing the sameair, it is desired to have air handling systems able to removecontaminants to prevent widespread exposure to a contagion. Further, inthe event of a catastrophic incident, governments and emergency responseagencies need to be able to quickly provide safe working conditions forhealth workers and other emergency responders to contain and destroycontaminants, whether natural or man-made, whenever and wherever may benecessary.

From the above, the need to provide safe air supplies may come upon apopulation suddenly, may be preferable but not necessarily required inanticipation of a potential release, or may be constant such as inhospitals or “clean rooms,” where the need for cleaned air is alwaysnecessary as environmental air is simply too dirty for the specializeduse to which the air is put. The need for decontamination may be knownor predicted or an increased risk may be known to be likely in somesituations. In other situations it may come without warning.

An airborne contaminant's danger level will generally depend onconcentration. The concentration of a contaminant in the air beingbreathed will generally need to be above a particular threshold or elseexposure is unlikely to cause concern. Most contaminants, ifsufficiently dispersed, are not particularly dangerous. Therefore,protection against contamination usually requires the ability to eitherprovide air which is known to be safe and has been stored for use duringthe contamination period, or to filter air which is contaminated toremove the contamination and provide safe air. The use of stored air isgenerally less effective as the storage requires specialized tanks andprocesses, and generally the amount of air which can be stored isrelatively small. Instead, filtration is generally used, particularly ifone is attempting to provide safe air to a group of individuals.

Filtration for harmful contaminants generally works by pulling some orall of the contaminant from the air into a solid filter. The resultingair is then provided to the users and generally only includes a reducedconcentration of the contaminant such that the levels are sufficientlylow that the contaminant is no longer harmful or, at the worst, nolonger debilitating.

To prevent introduction of contaminants later, the clean air isgenerally pumped into an isolation environment which preventsintroduction of unfiltered air and in which the individuals needing airare located. Smaller protective suits can provide an isolationenvironment for a single person while larger isolation structures canhouse multiple individuals. These isolation structures are, therefore,often the preferred method of providing safe air. Isolation structurescan have economies of scale for filtration where larger more powerfulair intake devices can be used to supply air to the structure. Further,a structure can allow individuals therein to perform tasks as theynormally would instead of being forced to work in cumbersome individualprotective suits.

Isolation structures may be permanent or may be temporary and may beused in any environment where safe air is needed. These environments maynot be suitable for human occupancy because air is contaminated, orbecause air simply does not exist. In emergency responses or militaryfield activities on the Earth, a temporary structure is generallypreferred as it can be quickly setup anywhere when needed, and moreeasily stored when not needed. Often the temporary structure isinflatable whereby the structure can be setup in the zone ofcontamination and can then be filled with clean air using a portablefiltration system to filter outside environmental air. The internal airpressure then provides the shape to the structure. Once inflated, thestructure will be able to provide a safe haven for multiple people and astaging point for the use of contamination suits to venture further intoa contaminated area. Further, the structure can often be provided withmore efficient heating, cooling, or other environmental control units(ECUs) than individual protective suits can include.

FIGS. 1 and 2 provide for a first embodiment of an isolation shelter, inparticular a collective protection shelter of the type commonly used bythe United States military. This structure is intended to be vehicleportable (as shown in FIG. 2) and is usually transported on a HighMobility Multipurpose Wheeled Vehicle (HMMWV or Humvee) (70). Oncedeployed, as it is in FIG. 1. the shelter (75) will have been inflatedand will comprise a self supporting isolation shelter. In the depictedembodiment, the shelter (75) comprises two structural “buildings”connected side-by-side. There is also an external airlock allowingaccess inside the shelter (75). The Humvee (70) is still attached to theshelter (75) and generally serves as a command and control center forthe shelter (75) as well as a power source via its engine to runcomponents in the shelter (75). In an embodiment, the collectiveprotection shelter will also generally have an environmental controlunit (ECU) (not shown) and may include an external generator.

Traditionally, on both portable filtration units and in permanentstructures, filtration was performed by use of deep bed activated carbonfilters or similar filters which block particles larger than aparticular size and/or that react with particles of a particular type.

While this type of system is well understood, filters of this type allsuffer from similar drawbacks In the first instance, changing the filtergenerally requires a potentially hazardous operation. As contaminantsare captured by the filter to clean the air, the filter therefore willcontain a high concentration of contaminants which will often make thefilter quite toxic. These contaminants are generally still dangerous andbiologically active within the filter material. Therefore, individualshandling the filter need to be careful that they are not accidentallyexposed to the contaminants or that they do not inadvertently introducethe concentrated contaminants into an unfiltered air stream. In manyrespects, the filter cleans the air while creating a dangerous solidwaste (namely the filter itself) which has to be safely disposed of toavoid later contamination. The contaminant is not eliminated by thefiltration, it is simply concentrated and captured in a more easilydisposable form.

Filters of the traditional type also have the problem of failing after acertain amount of time. As a filter is used, the ability of the filterto successfully filter out additional contaminants is often compromisedand a dirty filter can reintroduce contaminants to the filtered air.Further, as filters become full of contaminants the air flow is oftenslowed so that motors drawing air into the structure must work harder oran insufficient amount of air is provided. As humans generate carbondioxide while breathing, which is toxic to them, with insufficient cleanair flow into the system, air can rapidly become dangerous even ifoutside contamination is successfully removed

Filters are also part of the significant logistic trail in both militaryand civilian protection and can also be a significant expense. To date,there is no production system that incorporates a method to measure theabsorbent capacity level remaining in filtration material. In theabsence of this, protocol dictates that a filter be changed after apredetermined number of hours in service, irrespective of whether it hasfiltered contaminated air or not. This means that the filter is changedmore frequently than may be needed when it is in use to prevent anyunintended failure, Each change of filter requires personnel to leavethe isolation environment and to change the filter As well as being atedious and dangerous task, it offers the possibility that the newfilter might not seat correctly, leaving the system potentially at riskand introducing the danger that personnel may be exposed to thecontaminated air while outside the shelter.

One proposal to attempt to deal with the need to change filters isregenerative filtration whereby the filter can be remotely cleaned.There have been numerous different types of these proposed such aspressure swing, temperature swing, electronic swing and hybrid systemsthereof. Regenerative filtration systems, while effective, are bulky andconsume more power and, hence, are only useable in certain applications.Further, regenerative filters provide no energy recovery but actuallyuse additional energy to operate as they must have power to clean.Further, the regenerative filter cannot provide aid to the otherenvironmental control aspects of the ECU. The regenerative filter doesnot provide for heating or cooling of the air which must be provided bythe ECU. This makes the regenerative filter an expensive alternative.Finally, a regenerative filter is still generally a standard filter, andwhile it can self-clean is generally subject to the limitations on airflow and contaminant capture as a more traditional filter.

SUMMARY

Because of these and other problems in the art, described herein aresystems and methods for using supercritical water oxidation to purifyair. These systems and methods are generally designed to be portable andto allow for relatively high speed purifying of air.

Described herein, in an embodiment, is a method for generatingbreathable air comprising: having a supercritical water reactor (SCWR);providing said SCWR with water and raw air; said raw air comprisingoxygen and at least one organic contaminant; placing said water in asupercritical state thereby dissolving said contaminant into said water;allowing said oxygen in said raw air to completely oxidize saidcontaminant creating an effluent stream comprising oxygen, water andoxidation outputs; removing said effluent stream from said supercriticalstate; separating said water from said oxidation outputs and saidoxygen; and providing said oxidation outputs and said oxygen asbreathable air.

In an embodiment of the method, in said step of separating, aconcentration of at least one of said oxidation outputs is determinedand said concentration is altered prior to said step of providing.

In an embodiment of the method said raw air is air drawn from Earth'satmosphere and may further comprise nitrogen. In another embodiment,said outputs of oxidation include at least one of: hydrogen, carbondioxide, and carbon monoxide.

In another embodiment of the method, in said step of allowing; saidoxidation creates additional water, and said additional water is alsoremoved in said step of separating from other oxidation outputs and saidwater provided in said step of providing may be said water removed insaid step of removing from a prior occurrence of said method.

In another embodiment of the method, thermal or work energy is recoveredfrom said effluent stream for use in said step of placing. The pressureand temperature levels of said effluent stream may also manipulated toresult in the heating or cooling of said breathable air,

In another embodiment of the method, said raw air further comprises aninorganic contaminant which may be precipitated from said effluentstream,

In another embodiment, there is described herein, a system for purifyingair comprising: raw air comprising oxygen, nitrogen, and at least oneorganic contaminant; water; means for taking said water and said raw airand increasing pressure and temperature to make said watersupercritical; said supercriticality and the presence of said oxygen insaid raw air forming said organic contaminant into at least onedecomposition product, said water, oxygen, nitrogen, and at least onedecomposition product comprising an effluent stream; and means forseparating said water from said effluent stream; wherein at least one ofsaid at least one decomposition product is selected from the groupconsisting of: hydrogen, carbon dioxide, carbon monoxide.

In another embodiment of the system, there may be included means forrecovery of thermal energy from said effluent stream, means for recoveryof work energy from said effluent stream, or means for reducing thetemperature and pressure of said air stream to about 294K and about 1atm, respectively.

In a still further embodiment, there is described, a system forpurifying air comprising: feeds for raw air and input water; asupercritical water reactor (SCWR); a condenser; a heat exchanger; apressure exchanger; and a pressure regulator; wherein, said input waterand raw air are provided to said SCWR by said feeds; wherein, said inputwater, when in said SCWR, is in a supercritical state; wherein, in saidSCWR, a contaminant is removed from said raw air forming clean air;wherein, said SCWR releases said clean air and output water as aneffluent stream; wherein said heat exchanger removes thermal energy fromthe said effluent stream for use in raising the temperature of saidinput water and raw air; wherein said pressure exchanger removes workenergy from the said effluent stream for use in raising the pressurelevel of said input water and raw air; wherein said pressure regulatoradjusts the pressure level of said clean air to a particular pressurelevel according to its temperature level; and wherein, said condensercan separate said output water from said clean air

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 Provides a drawing of an embodiment of a collective protectionshelter deployed from a High Mobility Multipurpose Wheeled Vehicle(HMMWV or Humvee).

FIG. 2 Shows the collective protection shelter of FIG. 1 stored on boarda Humvee.

FIG. 3 Provides a graph showing the conditions of supercritical water.

FIG. 4 Provides a general block diagram of an embodiment of an SCWO airpurification system.

FIG. 5 Provides a graph showing various adiabatic process lines forvarious inlet temperatures and pressures.

FIG. 6 Provides a graph showing inlet pressure and temperature ratiosthat yield a 294 K outlet temperature.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

Disclosed herein, among other things, is a supercritical water oxidation(SCWO) system for converting raw air which may or may not contain anykind of contaminant, whether or not harmful to human beings or whetheror not present in sufficient quantities to harm human beings, into cleanair which may be safely breathed by humans. The raw air may be suppliedfrom any source of air but will generally be from atmospheric airavailable to the system.

The term “raw air” as used herein is intended to be a general termrelating to the gaseous material generally recognized as air whosepurification is desired. This will generally be because the raw air isviewed as not clean and contains a contaminant to be removed. However,the raw air is desired to be processed, even if such cleaning isunnecessary. Raw air generally will comprise air of the type generallyavailable in Earth's atmosphere regardless of exact chemical compositionand will usually include molecules of nitrogen and oxygen. Air will alsogenerally comprise a small percentage of other gases, such as, but notlimited to, carbon dioxide, and water vapor. The air may furthercomprise any number of contaminants which will generally be solidparticulates suspended in the air or particular gases.

A contaminant, as used herein, is essentially any material mixed with,suspended by, or in solution with the air in a sufficient concentrationthat breathing of the contaminated air can result in harm to humanbeings and specifically includes, but is not limited to, pollutants,microorganisms, biologicals, chemicals, particulates or other materials.One of ordinary skill in the art would recognize that some of thesecontaminants are not necessarily harmful. However, contaminants willhave little to no positive effect to the human body and could result inharm, even if the risk and harm is small. Most contaminants of interestwill be organic contaminants of the type forming chemical or biologicalwarfare agents (CBWAs) but that is not strictly required, and either orboth organic and inorganic contaminants can be included.

Generally, it will be presumed that the materials to be removed areeither biological or chemical in nature such as microorganisms, pollens,or other materials which have been placed in atmospheric air. It will berecognized that the contaminants in cases where the filtration systemsdiscussed below are most likely to be used have been purposefullyintroduced by man for the purpose of terrorism or as a weapon however,environmental contaminants such as pollen, dander, or naturalmicroorganisms, may also qualify as contaminants. Contaminants may bepresent in relatively small quantities over a relatively large area yetstill cause wide-spread contamination. The SCWO air purifier (50) willgenerally be presumed to be used in conjunction with an isolationshelter, in particular a Collective Protection Shelter as used by theU.S. Military. While this disclosure will focus on such systems inconjunction with a Chemically and Biologically Protected Shelter System(CBPSS), it would be recognized that any isolation shelter may be used,whether temporary or permanent and including, but not limited to:Chemically Protected Deployable Medical Systems (CP DEPMEDS), ChemicallyHardened Air Transportable Hospitals (CHATH), Simplified ProtectionEquipment (SCPE), or Joint Transportable Collective Protection Systems(JTCOPS).

To begin discussion on the removal of contaminants, it is useful tobegin with an understanding of supercritical water which is used in thepurification process.

FIG. 3 generally shows the region (10) where water exists in itssupercritical state. Supercritical water is recognized as having a veryhigh solubility for organic materials, and a very low solubility ofinorganic materials. Supercritical water is used to separate out bothorganic and inorganic contaminants from the raw air and then provide forclean air from the process.

FIG. 4 provides an embodiment of a block diagram showing the layout of asupercritical water oxidation (SCWO) air purifier (50) which can be usedto purify raw air into breathable air by using SCWO processes. In FIG. 4there are generally three broad component stages which relate to theoperation of the SCWO air purifier (50).

In the stage one components (100) raw air (515) and water (415) areinput into the system, placed under pressure and heated In the stage twocomponents (200), a supercritical water reactor (SCWR) (201) takes inthe pressurized and heated water and raw air mixture (615) and uses thewater (415) as a solvent and the oxygen in the raw air (515) as anoxidant to remove and/or destroy the contaminants from the raw air(515). In the stage three components (300), the water (415) is condensedand collected and the effluent air (315) is shuttled to the targetdestination. As part of the stage three components, the effluent air(315) may be cooled using properties of the pressurized air. Each ofthese component stages will now be discussed in more detail.

In the stage one components (100) there are two chemical feedsrepresenting the two inputs raw air feed (101) and input water feed(103). The raw air feed (101) is generally arranged so as to allow rawair (515) to be obtained from a pressurized air tank (102) from priorpumping of atmospheric air into the tank. The raw air feed (101)generally includes a compressor (112) to compress the raw air (515) toplace it under pressure. The compressor (112) preferably pressurizes theraw air (515) to a pressure level near the critical pressure of water(218 atm) shown in FIG. 3. The compressor (112) may increase thepressure using any system of method known now or later developed The rawair (515) will also generally pass through a preheater (107) which heatsthe raw air (515) to a point near the critical temperature of water(374° C.) as also shown in FIG. 3. The raw air in this case willgenerally be environmental air from the Earth's atmosphere outside ofthe isolation environment. The amount of air fed by air feed (101) iscontrolled by a flow controller (115) which will serve to insure thatthe correct amount of raw air (515) is supplied to the SCWR (201) toprevent air from passing through SCWR (201) without proper purification.The amount of raw air (515) fed into the SCWR (201) will generallydepend on the organic content (“purity”) of the raw air, and, in anembodiment, is determined during operation by the gas analysis takingplace near the end of the process stream in air tester (307). At aminimum, however, the amount of raw air (515) processed will need to besufficient to meet the make-up air flow required to ensure breathableair. Further, in a CBPSS, other inflatable isolation structure, or manyother isolation structures, the air flow will generally need to besufficient to maintain positive pressure inside the isolation structure.The raw air (515) fed by raw air feed (101) will generally comprise amixture of gases including nitrogen, oxygen and a relatively smallpercentage of various other gases which are not contaminants as well asat least one contaminant to be removed Generally, the nitrogen willcomprise about 78% of the mixture, oxygen about 21% of the mixture andthe other materials comprising about 1% of the mixture in accordancewith the composition generally accepted as Earth's atmospheric air. Forthe purpose of this disclosure, the exact composition of the gases priorto purification is not important. Instead, the purpose of the system isto produce outputs which can be combined into breathable air. Inparticular, the oxygen concentration is of particular importance as isthe level of carbon dioxide. Pursuant to Occupational Safety and HazardAdministration (OSHA) regulations, breathable air should include atleast 19.5% oxygen and no more than 1% carbon dioxide. For purposes ofthis disclosure, effluent (“clean” or “breathable”) air (315) willtherefore preferably have constituents in this range, however, any airwhich can be breathed by a human for some period of time without injuryis classified as clean or breathable air. In an alternative embodiment,pure nitrogen gas or other inert gases may also be provided on anadditional feed (105) to be used to purge the system.

The input water feed (103) includes a high pressure pump (104) and abooster pump (106) designed to feed input water (415) into the SCWO airpurifier (50) using any type of liquid feed technology known now orlater developed. The pump (104) preferably pressurizes the water (415)to a pressure level near the critical pressure of water (218 atm) shownin FIG. 3. Before the input water (415) is provided to the SCWR (201),it will generally pass through a preheater (107) which heats the waterto a point near the critical temperature (374° C.) also shown in FIG. 3.The raw air (515) and water (415) may be mixed prior to entering SCWR(201) as in the depicted embodiment forming an input raw air/watermixture (615) or may be mixed in the SCWR (201) in an alternativeembodiment. Generally, there will be valves (111) at various pointsbetween the air feed (101), water feed (103), and the SCWR (201) (and atother points in the SCWO air purifier (50)) to prevent back feed, toregulate the amount of each material provided in the raw air/watermixture (615), and to maintain the pressure inside the SCWR (201).

As mentioned above, the first stage components (100) may also include apurging system. The purge system will generally comprise a nitrogen orother inert gas feed (105) which may provide inert gas into the systemunder pressure This purge can be used to clean the system of residualmaterials during system shutdown or to clear out potentially dangerousair, contaminants, or other items which could get into the isolationenvironment.

Input water (415), in the embodiment of FIG. 4 comprises the water (415)output from the condenser (305) (as discussed later) which is re-fedinto the system. The input raw air/water mixture (615) may pass throughthe energy recovery system obtaining heat or pressure from the effluentstream (215) prior to insertion into the SCWR (201). In an alternativeembodiment, the water (415) separated from the effluent stream (215) maysimply be allowed to retain heat and/or pressure and be directly cycledback as input water (415) Heat may also be transferred to the rawair/water mixture (615) as a by-product from internal combustionprocesses or other engines or drivers which are operating the pump (104)or other components of the SCWR air purifier (50). These exchangers(503) and (505) may utilize any methods or means known to those ofordinary skill in the art to exchange heat and pressure from theeffluent stream (215) to the input water/air mixture (615) to help raisethe pressure and temperature levels of the input mixture (615). In thisway, the heat and pressure of the effluent stream (215) is recycled backinto the input stream (615) which helps to make the system run moreefficiently and require that less heat be generated by the heatingelements (223) or preheater (107), or less work be produced by pumps(104) and (106).

The recycling of heat and pressure and their use in the SCWO airpurifier (50) is also discussed later in conjunction with providing forcooling of the effluent air (315) to provide for efficient airconditioning when the system is used in hot environments. This however,occurs during the third stage components (300) and is discussed therein.

Returning to the walk through of FIG. 4, as the input mixture (615) ofwater (415) and raw air (515) enters the second stage components (200)it enters into the SCWR (201). The SCWR (201) is typically a vesselconstructed according to known high pressure design codes forHastelloy-C276, Inconel, or other suitable material. In an alternativeembodiment, the reactor may be constructed of stainless steel. The SCWR(201) may be either a mixing-type or continuous tubular type As depictedin FIG. 4, the SCWR (201) may be equipped to obtain additional heat froma heat source (223) which heats the input water/air mixture. Thisincludes the pre-heater (107) as well as additional heating elements(223) in the SCWR (201). Alternatively, heat exchange components may beincluded in the system as discussed above.

In the SCWR (201), the supercritical water drives an oxidation reactionto break down the organic contaminants present in the raw air into theirdecomposition products such as hydrogen, water, carbon dioxide (CO₂) orcarbon monoxide (CO). In particular, the supercritical water completelydissolves all organic materials likely to be present in the raw air. Allthese ingredients further will generally react completely with theoxygen in the raw air in a homogeneous reaction phase within the SCWR(201) resulting in creation of their decomposition products.

Unlike many other treatment processes, the process converts organicspecies into water, hydrogen, carbon monoxide, carbon dioxide and otherdecomposition products as opposed to simple filtration capture of thecontaminant. The decomposition products of organics are all generallyharmless so long as not provided in too high of a concentration. Asoxygen in the raw air is used up by the reaction and carbon dioxide iscreated, there is a very slight possibility that the resultant airproduced might not be breathable.

The amount of oxygen used, however, is generally very minimal (as thecontaminants are generally a very small percentage of the raw air(515)). Therefore, it is highly unlikely that sufficient oxygen would beused up to render the air unbreathable. Further, generally only arelatively small amount of carbon dioxide is created. If concentrationsof organics are sufficiently high to prove problematic, however, oxygenconcentration in an embodiment is increased by removing other materialsthrough the use of air scrubbers as is understood in the art.Alternatively, the air intake may be increased to provide more air flowIf carbon dioxide concentration is a concern, CO₂ scrubbers are added tothe effluent stream in an embodiment as discussed later. Inorganiccompounds, which are generally insoluble in the supercritical water canbe precipitated out as ash or salt from the SCWR. These can then beremoved. A solid particulate can be removed using any type of systemknown now or later discovered.

In the depicted embodiment, the SCWR (201) is monitored by a temperaturecontroller (221) which senses the internal temperature of the SCWR (201)and as necessary applies additional heat input to the SCWR (201) usingheating elements (223) to maintain the temperature in the SCWR (201)near the critical temperature of water. The pressure inside the SCWR(201) is preferably monitored by a back pressure regulator (235) tomaintain the pressure in the SCWR (201) near the critical pressure ofwater. A pressure relief valve (237) may also be present in case thepressure inside the SCWR (201) reaches dangerous levels. If such highlevels are detected, pressure will generally be released from SCWR (201)via a vent to prevent danger from explosion or similar risks.

Once the SCWR (201) has purified the air, the resultant effluent stream(215) which will include the clean air (315) as well as the input water(415) (which will also be very clean as a byproduct of the reaction) ispassed through a forward pressure regulating valve (211) and into thestage three components (300). Valve (211) generally serves to controlthe pressure of the effluent stream entering condenser (305).

The stage three components (300) are principally related to separatingwater (415) and effluent air (315) in the effluent stream (215) in auseful manner. Some or all of the water (415) may be removed dependingon the desired effluent air (315). In particular, some water (415) maypurposefully not be separated to provide more humid air to eliminatedryness for occupants. Water (415) which is separated out will generallybe stored in a storage vessel (311) until needed and then re-fed intothe SCWR (201) by the water feed (103). However, in an alternativeembodiment, the water (415) may be drained off to form a potable watersource due to the cleaning of the water which occurs in the SCWR (201)simultaneous to cleaning of the raw air (515). In an embodiment, rawwater in need of processing is fed into the SCWR (201) along with theraw air (515). The SCWR (201) then cleans both air and watersimultaneously. This embodiment provides for a powerful single systemfor both processes. The cleaning of water using SCWO is discussed inadditional detail in U.S. patent application Ser. No. 10/840,716, theentire disclosure of which is herein incorporated by reference.

The pressure and temperature in the stage 3 components (300) willgenerally be lowered to allow precipitation of the water (415) out ofits supercritical state. This pressure and temperature lowering may alsobe used to lower the temperature of the air to a comfortable “roomtemperature” without need for traditional air conditioning setups. Theprecipitation of water (415) will generally be performed by a condenser(305). The resultant liquid water is collected in the storage vessel(311) while the remaining oxygen and nitrogen gas (and other gases andsuspended particles, if present) will be sent to an air tester (307).The air tester (307) may include devices for altering the output air(such as scrubbers to remove excess carbon dioxide or carbon monoxide)as well as devices for evaluating whether or not the output air stillcontains any harmful contaminants. Presuming the air is determined to beclean, and the percentage of various components is also not toxic, theeffluent air (315) will generally be piped into the isolationenvironment as clean breathable air. If there is a problem with theeffluent air (315), the effluent air (315) may be cycled back throughthe SCWR (201), exhausted outside the isolation environment, or scrubbedto place the effluent air (315) in desired form.

Control of the SCWO air purifier (50) is performed in the embodiment ofFIG. 2 by monitoring the SCWR (201) effluent air stream (315) with theair tester (307). The air tester (307) will generally include a gaschromatograph or other suitable sensor to determine the composition ineffluent stream (215). From these results, a user can adjust the airfeed (101) and water feed (103) to control the residence time of the rawair/water mixture in the SCWR (201). The air tester (307) may controlair fed into the SCWR (201) by means of the mass flow controller (115)using automatic control, Alternatively, the system may be entirelyregulated by a user.

As the effluent air (315) is being provided to the user, the effluentair (315) will obviously need to be reduced from the supercriticalpressure and temperature of water which it was at in the SCWR (201) to acomfortable temperature to prevent injury from the heat. This return canprovide for an additional benefit of allowing temperature manipulationof the air without resort to traditional air conditioning type systems.In particular, the expansion of the air from the approximately 218 atmof pressure at the supercritical state to 2 or 1 atm which is thelogical pressure that the air would be provided is a reversibleadiabatic (isentropic) process. This pressure decrease can be carriedout by pressure transfer to the input raw air/water mixture. Further,the clean air will generally automatically decrease in pressure as it isejected into the isolation shelter as the isolation shelter willgenerally be pressured at slightly above 1 atm. Simple calculation ofthe pressure drop from 218 atm to 1 atm indicates that the air will infact be placed at a temperature significantly below freezing if justbeing exhausted from the SCWR (201) to the isolation shelter and wouldbe much too cold to be provided to a human user.

To control this temperature decrease to provide for useful cooling,without freezing, it is preferable to utilize a relationship as shown inFIG. 5. FIG. 5 provides an indication of the temperature at which theeffluent air (315) would end up in the shelter and somewhere downstreamover various air exhaust pressures for three different air exhausttemperatures (the temperature that the air would be exhausted into theshelter). As can be seen, if the desired shelter temperature is selectedas 294 K or about 70 degrees Fahrenheit at 1 atm of pressure, levels ofair exhaust temperature and pressure for the air can be selected toobtain that result as shown by the dashed line.

The indications of this graph can then be displayed as the graph of FIG.6. This graph provides that for the fixed room temperature (about 70degrees Fahrenheit) selected, there is a curve of air exhausttemperature(s) and pressures required to reach the desired roomtemperature at about 1 atm pressure. The system can then utilizepressure and heat exchange (energy recovery) as discussed in conjunctionwith the stage one components (100) above to place the effluent stream(215) at a desired pressure and temperature combination upon exhaust ofthe effluent air (315) into the shelter. Using this information, theeffluent air (315) will reach the desired temperature in the isolationshelter as it naturally adjusts to about 1 atm of pressure. Inparticular, at any point of this line, if the effluent air (315) isexhausted into the isolation shelter, at that pressure and temperature,the effluent air (315) will reduce to a comfortable temperature in theisolation shelter as its pressure naturally adjusts to about 1 atm.Noticing that any point on the line of FIG. 6 will result in effluentair (315) at 1 atm being the desired temperature, generally a lowerpoint on the line (lower temperature and pressure combination) will bechosen, in this way, most of the heat and pressure from the effluent air(315) may be removed through the heat and pressure exchangers (503) and(505) respectively allowing for recycling of these components in thesystem and improved efficiency. Once the desired point of exhausttemperature and pressure is reached (generally on or near the curve ofFIG. 6), the effluent air (315) is ejected and, given its prior state,will reduce to about one atmosphere of pressure (the pressure it is atin the ambient environment). As the effluent air (315) adjusts to thispressure, its temperature will continue to fall to the targettemperature allowing for the system to provide air at the targettemperature. If this air is used in a self contained structure, itshould be clear that the structure will therefore have air of acomfortable temperature even if air outside the structure is not acomfortable temperature.

The embodiment of FIG. 4 does not require a particularly large setup, orparticularly complicated operation. It should be apparent that the SCWOair purifier (50) could be assembled to be readily vehicle portable to avariety of locations. In particular, the SCWO air purifier (50) wouldpreferably be able to fit on a pallet such as a forklift pallet or a463L pallet as used by the United States Air Force. Alternatively, ascaled up version of the SCWO air purifier (50) could be placed in anover-the-road (OTR) truck trailer or on a pallet, crop, or flatrackutilized by Load Handling System (LHS) trucks such as the HEMTT-LHStruck used by the United States Army. Likewise, a sealed-down versioncould be used for protecting the occupants inside a vehicle.

There is generally no need to provide additional water to allow thereaction once a particular amount of water has been provided, and thewater will cycle in an endless loop through the system. In analternative embodiment as previously discussed, the supercritical airpurification technology may be combined with a supercritical waterpurifier such as that discussed in U.S. patent application Ser. No.10/840,716, the entire disclosure of which is herein incorporated byreference. In this embodiment, both raw air (515) and raw water may beprovided to the system together providing both clean air and clean wateras outputs. The percentage of each may be selected based on how much ofeach is needed as output (with excess being discarded or simply servingas a surplus), or to maximize the efficiency of the reaction. Regardlessof which method is used, in the SCWR (201) whether the contaminant wasoriginally waterborne or airborne is irrelevant. The contaminant will bedestroyed in the SCWR (201). Therefore both clean water and clean airwill be able to be removed from the system. Depending on which of theseproducts are to be used, one of these may be recycled or vented or bothmay be sent to final end users.

SCWO air purifiers (50) can be used in a wide variety of applicationsand for a wide variety of purification tasks. One such use is clearlymilitary use. Soldiers in the field may be exposed to numerous foreignagents including foreign germs. Further, many countries are known tohave arsenals of nuclear, chemical, or biological weapons which createdangerous air borne contaminants. Soldiers operating in theseenvironments can be provided with collective protection shelters inwhich to take refuge in the event that such a germ or other agent ispresent. This can help the soldiers to weather an attack utilizing theseweapons, and can also help to speed recovery from such agents and tominimize downtime from naturally occurring contaminants.

In an alternative embodiment, while the above presumes that the airinside the isolation shelter is clean and environmental air iscontaminated, it should be apparent that the system can work in thereversed configuration. In particular, the system can also be used forisolation of contaminated (and generally contagious) individuals. Forinstance, a dangerous germ agent with which some soldiers becomeinfected may be prevented from additional airborne contamination byplacing those soldiers into a quarantine ward. The air in this ward canbe purified using an SCWO air purifier (50) prior to returning the airto the ambient, or to providing the air to another shelter. Because theSCWR not only kills the germ, but will actually reduce it todecomposition products completely destroying its structure, the germ haslittle chance of causing further problems outside the isolationstructure and is very effectively eliminated.

The system also has clear indications for clean rooms such as inhospitals or in manufacturing facilities which require clean air toprevent damage to delicate manufactured components and which can requireisolation and quarantine. In these systems, organic components will bebroken down into readily identifiable gases which, if they present aproblem, can be scrubbed from the air by well known systems. Generally,these gases will not provide a problem as they will not interact withthe components so can remain in the air. Further, inorganic materialssuch as dust can be removed as ash utilizing separation systems in theSCWR and providing only gases to the facility. This can make thefacility simpler to utilize for those inside as well as actuallyimproving cleanliness by not simply filtering potentially dangerous ordestructive agents, but by actually destroying or separating them.

While the invention has been disclosed in connection with certainpreferred embodiments, this should not be taken as a limitation to allof the provided details. Modifications and variations of the describedembodiments may be made without departing from the spirit and scope ofthe invention, and other embodiments should be understood to beencompassed in the present disclosure as would be understood by those ofordinary skill in the art.

1. A method for cleaning air comprising: having a supercritical waterreactor (SCWR); providing said SCWR with water and raw air; said raw aircomprising oxygen and at least one organic contaminant; placing saidwater in a supercritical state thereby dissolving said contaminant intosaid water; allowing said oxygen in said raw air to oxidize saidcontaminant creating an effluent stream comprising oxygen, water andoxidation outputs; removing said effluent stream from said supercriticalstate; separating said water from said oxidation outputs and saidoxygen; and providing said oxidation outputs and said oxygen as outputair.
 2. The method of claim 1 wherein in said step of separating, aconcentration of at least one of said oxidation outputs is determinedand said concentration is altered prior to said step of providing. 3.The method of claim 1 wherein said raw air is air drawn from Earth'satmosphere.
 4. The method of claim 1 wherein said raw air furthercomprises nitrogen.
 5. The method of claim 1 wherein said outputs ofoxidation include at least one of: hydrogen, carbon dioxide, or carbonmonoxide.
 6. The method of claim 1 wherein said outputs of oxidationincludes carbon monoxide.
 7. The method of claim 6 further comprising:removing said carbon monoxide from said oxidation outputs prior to saidproviding.
 8. The method of claim 1 wherein in said step of allowing;said oxidation creates additional water, and said additional water isalso removed in said step of separating from other oxidation outputs. 9.The method of claim 1 wherein said water provided in said step ofproviding is said water removed in said step of removing from a prioroccurrence of said method.
 10. The method of claim 1 wherein thermalenergy is recovered from said effluent stream for use in said step ofplacing.
 11. The method of claim 1 wherein work energy is recovered fromsaid effluent stream for use in said step of placing.
 12. The method ofclaim 1 wherein the pressure and temperature levels of said effluentstream are manipulated to result in the heating or cooling of saidoutput air.
 13. The method of claim 1 wherein said raw air furthercomprises an inorganic contaminant.
 14. The method of claim 13 whereinsaid step of allowing said inorganic contaminant is precipitated fromsaid effluent stream.
 15. A system for cleaning air comprising: raw aircomprising oxygen, nitrogen, and at least one organic contaminant;water; means for taking said water and said raw air and increasingpressure and temperature to make said water supercritical; saidsupercriticality and the presence of said oxygen in said raw air formingsaid organic contaminant into at least one decomposition product, saidwater, oxygen, nitrogen, and at least one decomposition productcomprising an effluent stream; and means for separating said water fromsaid effluent stream; wherein at least one of said at least onedecomposition product is selected from the group consisting of:hydrogen, carbon dioxide, carbon monoxide.
 16. The system of claim 15further comprising: means for recovery of thermal energy from saideffluent stream.
 17. The system of claim 15 further comprising: meansfor recovery of work energy from said effluent stream.
 18. The system ofclaim 15 further comprising: means for reducing the temperature andpressure of said air stream to about 294K and about 1 atm, respectively.